Back in the 1970s, biologists began to observe a remarkable social phenomenon in bacteria. They had long been aware that individual bacteria could sense and seek out nutrients in their environment, a phenomenon known as chemotaxis.
What they hadn’t realized was that bacteria could communicate between themselves using signaling molecules. In this way, bacteria can sense the presence of others and regulate their behavior accordingly, such as becoming bioluminescent or forming biofilms when their density reaches a certain critical level.